Write an expression for the kinetic energy of an object.

$A$ force of $7\, N$ acts on an object. The displacement is $8\, m$ in the direction of the force. What is the work done in this case (in $, J$)?

$A$ battery lights a bulb. Describe the energy changes involved in the process.

In each of the following cases,a force,$F$ is acting on an object of mass,$m$. The direction of displacement is from west to east,shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative,positive,or zero.

An object of mass $40\, kg$ is raised to a height of $5\, m$ above the ground. What is its potential energy? If the object is allowed to fall,find its kinetic energy when it is half-way down.

$A$ mass of $10\, kg$ is at a point $A$ on a table. It is moved to a point $B$. If the line joining $A$ and $B$ is horizontal,what is the work done on the object by the gravitational force? Explain your answer.